House training dgos who have become set in their ways can be a tricky situation but it definately is not impossible. I tend to bring them out (let them do the walking themselves unless it is totally impossible, because it reinforces where they are going) to the garden every hour to go, give them 5/10 mins and then go back in and try again another hour later until they go (and masses of praise is given... maybe even a nice treat!). If they do go in the house, bringing the dog to where they went and showing it to them (but don't shove their faces in it, that's terrible), saying a very firm "no/bold etc" and putting them out for a few mintues gives them the messege that they are bold and this is the place to go. It will take a good bit of patience but I have done this with several dogs and it does work (even though your own sanity will be tested!)

I agree with Karlin that you should treat the new dog as a rescue - home life will be very different for her and she will need time to get used to it. Establishing that you are the good guy may take time but all the hard work will pay off - good luck